1. Field of the Invention
The present invention relates to the trimming of the temperature control contents of an on-chip thermal sensor (thermometer assembled in a chip).
2. Description of the Related Art
Highly efficient semiconductor integrated circuits execute computations in parallel with each other at a high speed, from which a problem arises in that a chip temperature is increased.
When the chip temperature becomes higher than a certain limit, the transistors in the chip become in danger of breakage or firing. Therefore, technologies for controlling the chip temperature and preventing these failures of transistors are required.
One of the technologies is to assemble a thermal sensor in a semiconductor integrated circuit and to reduce a computation speed or stop a computation itself when a chip temperature exceeds a predetermined value (refer to, for example, Jpn. Pat. Appln. KOKAI Publication No. 10-4 1466).
In the technology, a trimming data which determines the temperature control contents of a thermal sensor is stored in a fuse circuit after a trimming test is executed to calibrate the temperature of the thermal sensor, for example, before a product is shipped.
However, in a conventional trimming test, since a signal path used in a normal operation is used as it is, a power source voltage is supplied to a core in a chip in a test. Accordingly, the test cannot be executed accurately due to the heat generated by a leakage occurring in the core.